Nitrogenous heterocyclic carboxyal-kylmercapto polyoxyalkylene ester photographic sensitizer



United States Patent 3,084,044 NITROGENOUS HETEROCYCLIC CARBOXYAL- KYLMERCAPTO POLYOXYALKYLENE ESTER PHOTOGRAPHIC SENSITIZER Fritz Dersch and Millet R. De Angelus, Binghamton,

N.Y., assignors to General Aniline & Film Corporation, New York, N.Y., a corporation of Delaware N0 Drawing. Filed Dec. 9, 1960, Ser. No. 74,786 19 Claims. (Cl. 96-456) This invention relates to photographic materials. More particularly, this invention relates to photographic materials sensitized by means of water soluble heterocyclic compounds in which a heterocyclic nucleus is linked to a polyoxyalkylene chain by means of a carboxyalkylcercapto group.

It is well known that polyalkylene oxides such as polyoxyethylene and polyoxypropylene increase the speed of silver halide emulsions. It has also been observed that condensation products of alkylene oxides with amines, carboxylic acids, alcohols, amides or phenols (made according to United States Patents 1,970,578 and 2,213,477) and dicyclohexylol-dialkyl methane (see United States Patent 2,240,472) have been used as sensitizers. The polyalkylene oxides or the alkylene oxide condensation products should have a molecular weight of at least 300 and preferably 1,500 to 4,000 or more.

The use of the polyalkylene oxides or alkylene oxide condensation products as sensitizers is limited because of their tendency to increase the formation of fog during storage of the photographic film, especially storage at elevated temperature and high humidity. Th use of conventional antifoggants is not suflicient to satisfactorily eliminate or minimize fog formation in a film coated with an emulsion containing such products as sensitizers. Special antifoggants had to be found for use with such emulsions; and, in this connection, reference is made to United States Patents 2,704,716, 2,716,062 and 2,728,666.

It is an object of this invention to provide a novel sensitizer for use with a photographic emulsion or with a photographic developer to greatly increase the speed of the emulsion without materially increasing the fogging tendency thereof, any tendency to fog being eliminated or minimized by the use of conventional antifoggants.

Another object of this invention is to provide a photographic film having a layer thereon containing a water soluble polyoxyethylene ester of Z-carboxyalkylmercaptoazoles or the terminal alkyl ethers of such esters.

Other objects and advantages of this invention will appear to those skilled in the art from the detailed description thereof given below.

We have now discovered that water-soluble polyoxyalkylene esters of 2carboxyalkylmercapto-azoles as well as the terminal alkyl ethers of such esters have a remarkable speed increasing effect on silver halide emulsions. Surprisingly, these heterocyclic derivatives, unlike the heretofore used polyoxyalkylenes, do not have the objectionable tendency of increasing the fog of photographic films during storage especially under high temperature and humidity conditions. fogging of photographic film having a coating of a silver halide emulsion and containing the novel sensitizer of our invention may, therefore, be controlled by the use of the conventional antifoggants and stabilizers used in the photographic art. Consequently, the use of a special type of antifoggant to prevent fogging of an emulsion containing unhalogenated polyoxyalkylenes such as those disclosed in United States Patents 2,704,716, 2,716,062 and 2,728,666 becomes unnecessary.

3,084,044 Patented Apr. 2, 1963 ICC I The heterocyclic compounds contemplated for use here- 1n have the following general formulae:

wherein X represents the carbon atoms necessary to complete a five-membered heterocyclic nucleus; Y represents -S-, --0, ---NH--- or CH=CH (oxygen, sulfur, imino or vinylene); Z represents the atoms necessary to complete an aromatic nucleus of the benzene or naphthalene series so that X and Z together form a benzoxazole, naphthoxazole, benzothiazole, naphthiazole, benzimidazole or quinoline nucleus; R1 and R2, which may be alike or different, are alkylene groups having from 2 to 3 carbon atoms as represented by ethylene and propylene groups; R represents hydrogen or an alkyl radical having from 6 to 18 carbon atoms, for example, hexyl, octyl, nonyl, decyl or dodecyl; n is an integer ranging from 1 to 3 and m is an integer between 5 and 40 so as to give this compound a molecular weight of at least 400.

Examples of compounds within the ambit of this general formula are:

Ester of 2carhoxymethylmcrcaptobenzothlazole and dodecyloxypolycthyleneoxy-ethanol C-C3H COOCzH O(C:H O) C sTIn Ester of 2-carhoxyethylmercapto-d-chlorobenzothlnzole and hexadecylorry-polyethyleneoxyethanol Ester of 0ctadecyloxy-polyethylcneoxy-ethano] and 2-cnrboxypropylinercapto-5-nitrobenzot11iazole Ester of dodecyloxy-polyethyleneoxy-ethnnol and firm-boxymetllylmercupto5,ddimethylbcnzothiazole Ester of liexadecyloxy-polyothyloneoXy-ethunol and 2-cnrboxyethylrncrcapto hdhcnzobcnzotlliazole os -oH,o o o orno mo rno o mo memo roam, orno- Ester of dodecyloxy-polyproglyleneoxy-propanol and 2- carboxymethylmercaptd -methoxybenzothiazo1e Ester of dodecyloxy-polyethyleneoxyethanol and 2-carboxymethylmercuptobenzimidnzole C-S CH:C 0 001120 IIzO-(C H16 H10) mC 1110111011 Polyethyleneoxy ester of 2-carboxymethylmercaptooxazole Ester of dodecyloxy-polyethyleneoxy-ethnnol and 2-carboxymethylmercaptothiuzoline H CS C-SC*H;0O0CII CJII1O(C;IH O)[11-43 m OHnC-N Ester of d0dccyloxy-polyethyleneoxy-ethanol and 2-carboxymethylmercaptothiaaolidine The above compounds are prepared by refluxing a 2-mercaptoazole with the lower alkyl ester of a chloro or bromoaliphatic acid such as ethyl bromoacetatc, methyl chloroacetate, ethyl-,B-bromopropionate, methyl-'y-bnomobutyrate and the like in the presence of an acid-binding agent such as sodium hydroxide, pyridine and the like and then converting the lower alkyl ester of the carboxyalkylmercaptoazole thus obtained into the polyoxyalkylene ester by heating the azole in the presence of a suitable solvent diluent such as toluene or xylene with a polyoxyalkylene or polyoxyalkylene alkyl ether. This reaction is of the ester exchange type so that the lower alcohol which is used in the starting material is driven off during the reaction.

In an alternate method, the polyoxyalkylene alkyl ether is treated with thionyl chloride to replace its terminal hydroxy group by a chloride. The chloride derivative is then reacted with the alkali metal salt of a carboxyalkylmercaptoazole to yield an oxy product.

Examples of polyoxyalkylene ethers which can be used in the preparation of the hcterocyclic esters include the following:

Among the azoles suitable as starting materials are the following: 2-mercaptobenzimidazolc, Z-mercaptoquinoline, 2-mercapto-4-methylquinoline, Z-mercaptobenzoxazole, 2 mercapto 5 mcthylbenzoxazole, 2-mercapto-5- methoxy-bcnzoxazole, 2-mercapto-4,5-benzobenzoxazole,

2-n1ercaptobenzothiazolc, 2mercapto-S-mcthyl-benzothiazole, Z-mercapto-5methoxy-benzothiazole, 2-mercapto- 4,5 benzobenzothiazole, Z-mercapto-S-chlorobenzlothiazole, Z-mercapto-S-nitro-bcnzothiazole, 2-mercapto-5,6-dimethylbcnzothiazole and the various analogues and homologues thereof.

The increase of effective sensitivity of photographic silver halide emulsions with the polyoxyalkylene esters of the 2-carboxyalkylmercapto azoles can be obtained in a number of ways. They may be added to an undercoating, to a middle coating, to an overcoating or to a surface coating prior to the coating operation. If desired, they may be added during the actual preparation of the emulsion either before or after washing of the emulsion.

The speed of sensitivity increasing agents of our invention may be used in various types of photographic emulsions; for example, nonsensitized emulsions, orthochromatic, panchromatic, and X-ray emulsions. If used with sensitizing dyes, they may be added to the emulsion before or after the dyes are added. Various silver salts may be used as a sensitive element; such as, silver bromide, silver iodide, silver chloride or mixed silver halides. These sensitivity increasing agents may be used in emulsions intended for color photography; for example, emulsions containing color-forming components. The carrier in the photographic emulsion may be gelatin or other colloids such as collodium, albumen, cellulose derivatives, polyvinyl alcohol or synthetic resins. The emulsion containing our novel sensitizer may be coated on any conventional base such as paper, glass, cellulose ester such as cellulose acetate, cellulose ethers and others.

The amounts of sensitivity increasing agents used per kilogram of emulsion range from 0.15 to 5.0 grams per kilogram of liquid emulsion. When expressed in terms of silver halide, the amounts of sensitivity increasing agents range from 0.25 to 5.0 grams per mole of silver halide.

The sensitivity increasing agents of our invention can also be added to prc-bath solutions or to standard developer solutions. These developer solutions contain, in addition to the speed increasing agent, a developing agent such as Metol, hydroquinone, 1-phenyl-3-pyrazolidone (Phcnidone); an alkali such as sodium or potassium carbonate; a preservative or anti-oxidant such as sodium sulfite; and an antifoggant such as potassium bromide. The amounts of speed increasing agents used range from 0.3 to 6.0 grams per liter of developer solution.

The following specific examples are given of the manner of producing and using the sensitizers of our invention. It is to be understood, however, that these examples are given by way of illustration and not by way of limitation.

Example I A silver halide emulsion in gelatin containing 4 percent silver iodide and 96 percent silver bromide was prepared in a conventional manner and brought up to its maximum light sensitivity. It was then readied for coating on film base; that is, melted at 40 C. The necessary coating finals were added, such as sensitizing dyes, stabilizers and hardeners. A 10 percent aqueous solution of the above-illustrated ester of 2-carboxymethylmercaptobenzothiazole and polyoxycthylene lauryl ether was prepared, and measured amounts of this solution were added to a sample of the above-described emulsion con- Grams Metol (p-methylaminophenol sulfate) 1.5 Sodium sulfite, anyhydrous 45.0 Sodium bisulfite 1.0 Hydroquinone 3.0 Sodium carbonate, monohydrated 6.8 Potassium bromide .8

Water to make 1.0 liter.

The developed films were short-stopped, fixed and washed in the conventional manner. The results obtamed were as follows:

Fog

Relative Speed 6 Days After 12 Oven Dev. Test and 6 Dev.

Quantity of ester of 2-carhoxymethlymereaptobenzothiazole and polyoxyethylcnc lauryl ether:

0 D 13 .08 0 5 gram 150 15 .08 1.0 gram 16D .20 .09 Quantity of polyoxyethylene lauryl ether added:

1.0 gram 150 28 16 The ester of Z-carboxymethylmercaptobenzothiazole and polyoxyethylene lauryl ether which served as a sensitiner was prepared as follows: Twenty grams of polyoxyethylene lauryl ether (commercially available as Atlas Powder Companys Brij-) and 1.1 grams of Z-Carbethoxymethylmercaptobenzothiazole (prepared by the reaction of Z-mercapto-benzothiazole and ethyl bromoacetate) were added to milliliters of toluene. The mixture was heated to reflux for 8 hours, the toluene removed by distillation and the residue dried over phosphorus pentoxide in a dessicator. Seventeen grams of a light tan, waxy compound was obtained.

Example II QS-CgH5COO-CH:CH2O(CHgCHzO) CmH 3 Cl The procedure was the same as in Example I except that the reaction product of polyoxyethylene-hexadecyl ether and 2-carbethoxyethylmercapto-S-chlorobenzothiazole was used. The results were similar to those obtained in Example I.

Example III The procedure was the same as in Example I except that there was used the ester of polyoxyethylene lauryl ether and 2-carbethoxymethylrnercaptoquinoline. The reresults were similar to those of Example I.

The compound was prepared by heating in toluene polyoxyethylene lauryl ether and Z-carbethoxymethylmercaptoquinoline.

6 Example IV The procedure was the same as in Example I except that the reaction product of Z-carboxymethylmercaptobenzothiazole and 8 moles of propylene oxide iodide was used. The results were similar to those obtained in Example I.

The compound was prepared by heating under reflux 1 mole of Z-carbethoxymethylmercaptobenzothiazole and 1 mole of propylene oxide for 1 hour using a small amount of potassium hydroxide. Additional increments of propylene oxide were added while heating and refluxing continued until a total of 8 moles of propylene oxide had been consumed.

Example V GIL-S o-sornooo-omemooinornmm-onmi H:-N/ The procedure was the same as in Example I except that the reaction product of 2-carbethoxymethylmercaptothiazolidine and polyoxyethylene lauryl ether was used. The results were similar to those obtained in Example I.

Example VI One kilo of a silver halide emulsion in gelatin containing 4 percent silver iodide and 96 percent silver bromide was coated on film base in a manner known to the art. After the coating was performed, an aqueous gelatin solution containing 20 grams of gelatin per liter and 20 milligrams of the heterocyclic polyoxyethylene derivative of Z-mercaptobenzimidazole of Example I was coated thereon as an anti-abrasion layer. After drying, film samples were exposed and processed as described in Example I. The samples described exhibited a relative speed of with a fog of .18 as compared with a type coating of the same emulsion having an anti-abrasion layer similar to that described above, but lacking the speed increasing additive and having a speed of 100 and a fog of .22.

Example VII Several samples of a conventional photographic film were exposed in a type 1113 sensitometer and then divided into two groups. One group of samples was developed for twelve minutes at 68 F. in a standard Metol-hydroquinone developer as described in Example I. The other group of samples was developed for the same length of time and at the same temperature as the first group in a Metol-hydroquinone developer which had been prepared by adding to 1 liter of the developer described in Example I, 2 grams of the polyoxyethylene lauryl ether of 2-carboxymethylmercaptobenzothiazole. It was found that the samples developed in the standard developer had a relative speed of 100 whereas the samples developed in the developer containing the novel sensitivity increasing agent of our invention showed a relative speed of without an increase in fog.

Modifications of the invention will occur to persons skilled in the art. Thus, it is evident that in lieu of the ethylene oxide addition products of the examples, any of the addition products mentioned above may be employed in our invention. In place of the specific polyoxyethylene derivatives used in the reaction with the 2- carboxyalkylrnercapto azoles or their esters for the preparation of our novel speed sensitizing agents, there may be used the condensation products of alkylene oxide with amines, carboxylic acids, amides or phenols as prepared according to United States Patent 1,970,578.

We, therefore, do not intend to be limited in the patent granted except as necessitated by the appended claims.

We claim:

1. A photographic material comprising a light-sensitive emulsion having in contact therewith a water-soluble nitrogenous heterocyclic carboxyalkylmercapto polyoxyalkylene ester having a molecular weight of at least 400 to increase the sensitivity thereof.

2. A light-sensitive silver halide emulsion containing as a sensitizer therefor, a water-soluble heterocyclic polyoxyalkylene compound selected from the group consisting of those having the following general formulae:

wherein R and R are alkylene groups containing from 2 to 3 carbon atoms; R is a member of the group consisting of hydrogen and alkyl groups of from 6 to 18 carbon atoms; X represents the carbon atoms necessary to complete a S-membered heterocyclic nucleus; and Y represents the atoms necessary to complete a heterocyclic mononuclear ring and is a member selected from the group consisting of oxygen, sulfur, imino and ethylene; Z represents the atoms necessary to complete an aromatic ring system of the benzene and naphthalene series; 11 is an integer ranging from 1 to 3 and m is an integer between 5 and 40.

3. A light-sensitive silver halide emulsion containing as a sensitizer therefor, in a sensitizing amount, a compound having the following formula:

C-S-CII2COOGIT2GU2O(CIIzCIIgO) G 2lI25 wherein In is an integer between 5 and 40.

4. A light-sensitive silver halide emulsion containing as a sensitizer therefor, in a sensitizing amount, a comwherein m is an integer between 5 and 40.

5. A light-sensitive silver halide emulsion containing as a sensitizer therefor, in a sensitizing amount, a compound having the following formula:

6. A photographic material comprising a base, a layer of gelatino silver halide emulsion thereon and in contact with said emulsion a water-soluble ester of a carboxyalkylmercaptoazole and a polyalkylene oxide said emulsion having the following general formulae:

1 s x o so1-ri),,-co o-n10-(Ri0)mm N and wherein R and R are alkylene groups containing from 2 to 3 carbon atoms; R is a member of the group consisting of hydrogen and alkyl groups of from 6 to 18 carbon atoms; X represents the carbon atoms necessary to complete a S-membered heterocyclic nucleus; and Y represents the atoms necessary to complete a heterocyclic mononuclear ring and is a member selected from the group consisting of oxygen, sulfur, imino and ethylene; Z represents the atoms necessary to complete an aromatic ring system of the benzene and naphthalene series; n is an integer ranging from 1 to 3 and m is an integer between 5 and 40.

7. A photographic material comprising a base, a silver halide emulsion layer and in contact with said emulsion, a layer containing a compound of the following formula:

wherein m is an integer between 5 and 40.

9. A photographic material comprising a base, a silver halide emulsion layer and, in contact with said emulsion, a layer containing a compound of the following formula:

10. A photographic material comprising a base and a gelatin silver halide emulsion layer containing in a sensitizing amount a compound having the following formulae:

wherein R and R are alkylene groups containing from 2 to 3 carbon atoms; R, is a member of the group consisting of hydrogen and alkyl groups of from 6 to 18 carbon atoms; X represents the carbon atoms necessary to complete a S-membered heterocyclic nucleus; and Y represents the atoms necessary to complete a heterocyclic mononuclear ring and is a member selected from the group consisting of oxygen, sulfur, imino and ethylene; Z represents the atoms necessary to complete an aromatic ring system of the benzene and naphthalene series; n is an integer ranging from 1 to 3 and m is an integer between 5 and 40.

11. A photographic material comprising a base and a light-sensitive silver halide emulsion layer containing in a sensitizing amount a compound having the following formula:

wherein m is an integer between 5 and 40.

wherein m is an integer between and 40.

13. A photographic material comprising a base and a light-sensitive silver halide emulsion layer containing in a sensitizing amount a compound having the following formula:

14. The process of increasing the sensitivity of a lightsensitive silver halide material comprising a base having a light-sensitive silver halide emulsion thereon which comprises exposing said emulsion and developing the same in the presence of a water-soluble heterocyclic polyoxyalkylene compound selected from the group consisting of those having the following formulae.

wherein R and R are alkylene groups containing from 2 to 3 carbon atoms; R is a member of the group consisting of hydrogen and alkyl groups of from 6 to 18 carbon atoms; X represents the carbon atoms necessary to complete a S-membered heterocyclic nucleus; and Y represents the atoms necessary to complete a heterocyclic mononuclear ring and is a member selected from the group consisting of oxygen, sulfur, imino and ethylene; Z represents the atoms necessary to complete an aromatic ring system of the benzene and naphthalene series; n is an integer from 1 to 3 and m is an integer between 5 and 4O.

15. The process as defined in claim 14 wherein said compound has the following formula:

wherein m is an integer between 5 and 40.

16. The process as defined in claim 14 wherein said compound has the following formula:

wherein m is an integer between 5 and 40.

17. A photographic developer solution comprising a silver halide developing agent, an alkali, an anti-oxidant and an antifoggant containing as a speed-increasing agent, a water-soluble heterocyclic polyoxyalkylene compound having the following general formulae:

wherein R and R are alkylene groups containing from 2 to 3 carbon atoms; R is a member of the group consisting of hydrogen and alkyl groups of from 6 to 18 carbon atoms; X represents the carbon atoms necessary to complete a S-rnembcred heterocyclic nucleus; and Y represents the atoms necessary to complete a heterocyclic mononuclear ring and is a member selected from the group consisting of oxygen, sulfur, imino and ethylene; Z represents the atoms necessary to complete an aromatic ring system of the benzene and naphthalene series; n is an integer ranging from 1 to 3 and m is an integer between 5 and 40.

18. The developer solution as defined in claim 17 wherein said compound has the following formula:

wherein m is an integer between 5 and 40.

19. The developer solution as defined in claim 17 wherein said compound has the following formula:

wherein m is an integer between 5 and 40.

References Cited in the file of this patent UNITED STATES PATENTS 2,819,965 Murray et al. Jan. 14, 1958 2,952,539 Dersch et al. Sept. 13, 1960 2,955,037 Smith Oct. 4, 1960 

17. A PHOTOGRAPHIC DEVELOPER SOLUTION COMPRISING A SILVER HALIDE DEVELOPING AGENT, AN ALKALI, AN ANTI-OXIDANT AND AN ANTIFOGGANT CONTAINING AS A SPEED-INCREASING AGENT, A WATER-SOLUBLE HETEROCYCLIC POLYOXYALKYLENE COMPOUND HAVING THE FOLLOWING GENERAL FORMULAE: 